Rotor-slot ventilation for dynamoelectric machines



INVENTORS. Harry E C'rl'ner a Bennie A.R0se.

ATTORNEY an 4 w mm! 6 2 n 4 w -J n 4 I. 6 z m:

Aug. 19, 1947. H. E. CRINER ET AL ROTOR-SLOT VENTILATION FOR DYNAMOELECTRIC MACHINES Filed June '14, 1944 WITNESSES:

Patented Aug. 19, 1947 ROTOR-SLOT VENTILATION FOR DYNAMO- ELECTRIC MACHINES Harry E. Criner and Bennie A. Rose, Forest Hills,

Pa., assignors to Westinghouse Electric Corporation, East Fittsburgh, Pa., a corporation of Pennsylvania Application June 14, 1944, Serial No. 540,298

4 Claims.

Our invention relates to means for ventilating the winding-portions which lie in slots of a core of a dynamo-electric machine, and it has particular relation to such ventilation of the directcurrent field-windings on the high-speed rotormembers of turbo-generators.

Our invention is animprovement over the turbo-generator rotor of the Baudry Patent 2,221,567, granted November 12, 1940, and assigned to the Westinghouse Electric & Manufacturing Company. It is also an improvement over all previously known constructions for accomplishing a similar purpose.

The principal object of our invention is to provide a novel form of air-path, and a novel form of slot and tooth geometry, which will result in a considerable saving in cost, because of the elimination of rotor-drilling for discharge-openings, while at the same time increasing the efficiency of the ventilation by providing a smooth entry of the ventilating-air into the radial dischargeholes which we provide through the slot-closing wedges.

A more specific object of our invention is to provide a novel rotor-construction in which each winding-receiving slot has an axially extending ventilating-space on at least one side of the stack of winding-portion layers which are contained in that slot, in combination with slot-closing wedge-means having one or more radial ventilating-openings therethrough in communication with the ventilating space or spaces of its slot and in approximate radial alignment therewith.

A still further object of our invention is to provide a novel winding, comprising a stack of winding-layers in each slot of the core, these slotlying winding-layers comprising strap-conductors having internesting stacking-bulges for holding said stack in alignment, in combination with flat end-turn connectors which are connected to the ends of the several layers of the several slot-lying winding-portions, said flat end-turn connectors being stacked in a plurality of stacks without stacking-bulges.

With the foregoing and other objects in view, our invention consists in the systems, combinations, structures, parts and methods hereinafter described and claimed, and illustrated in the accompanying drawing, in which:

Figure 1 is a fragmentary longitudinal View of a large turbo-generator, partly in section,

Fig. 2 is a fragmentary, somewhat diagrammatic, developed winding-layout diagram,

Fig. 3 is a radial longitudinal cross-sectional view showing two of the layers of a winding- 2 stack, the section-plane being indicated by the line III--III in Fi 2.

Fig. 4 is a transverse sectional perspective view through the rotor-core, the section-plane being indicated by the line IVIV in Fig. 1, and

Fig. 5 is a transverse sectional view of two of the stacked slot-lying winding-layers, the section-plane being indicated at V-V in Fig. 3.

As shown in Fig. 1, our invention applied to a synchronous turbo-generator which has a statorcore I composed of annular laminations assembled together in groups or stacks, with radial ventilating-ducts 2 therebetween. The statorcore I carries the coils 3 of a polyphase primary winding of any desired type.

The machine also has a rotor which consists of a cylindrical core-member 4 having a plurality of axial or longitudinal slots 5 formed therein for the reception of insulated conductors 8 constituting the coil-sides or slot-lying portions of the field-winding. The conductors extend axially outwardly from th core to insulated end-connections 1 which are held in place by a retainingring 8 and an end-plate 9. Apertures l8 are provided in the end-plate to permit the entrance of a suitable gaseous cooling medium which may be either air or hydrogen, and apertures H are formed in the retaining-ring for permitting some of the cooling fluid to flow radially past the endconnections 1, While the rest of the cooling medium flows longitudinally into the slots for the purpose of cooling the conductors contained therein.

According to our invention, each of the rotorslots 5 is provided with an axially-extending ventilating-space l2 on at least one side of the stack 13 of slot-lying winding-portions 6 in that slot, each stack of slot-lying winding-portions having the bottom of the stack disposed near the bottom of its slot, and having the top of the stack extending up towards the slot-openingat the top of the slot. Preferably, the teeth 14 between the slots l3 of the rotor-core 4 are of approximately the same circumferential cross-section throughout their lengths, so that the slots 5 are wedgeshaped, being wider at their tops than at their bottoms. The stack l3 of coil-sides 6 is preferably centrally located in each slot 5, so that there are two wedge-sectioned longitudinal ventilatingspaces I2, on opposite sides of the winding-stack, in each slot 5.

According to our invention, the mouth or peripheral opening I5 of each rotor-slot 5 is substantially or nearly as large as the largest portion of the slot, at the top of the stack l3 of the field-winding coil-sides i therein, and this large slot-opening is closed by a slot-closin wedgemeans I6 which is provided, at desirable points, with radial ventilating-holes I! which are in communication with the respective axially extending ventilating-spaces l2, and in approximate radial alignment therewith, so that the ventilating fluid has a smooth entry into these discharge-holes I? in the wedge-means l6, as shown by the arrow i8 in Fig. 4. The wedge-means I8 is preferably made of aluminum or other light-weight material, and it may conveniently be made in short lengths so that a number of short wedge-sections IE will be utilized to close each slot 5. The radial discharge-holes IT in the wedges may then con- Veniently be made in the form of slots [1 in the ends of the respective short lengths of wedges 16, or in as many of them as may be desirable, as shown in Fig. 4.

The coil-sides or winding-layers 6 of each slotlying stack l3 of the winding are preferably formed of strap-conductors having internesting stacking-bulges 20, as shown in Fig. and this constitutes a well-known and convenient means for holding the stack in alignment,

It is very desirable, however, that the endturn connectors or winding-portions 1 shall not be provided with stacking-bulges, because, as shown in Fig, 2, these connectors must be bent laterally into U-shaped formation, and also bent in a circumferential direction around the rotor, so that they would not nest properly if the had stacking-bulges therein. In accordance with our invention, therefore, we make the end-turn connectors I out of fiat strap-conductors, which can readily be stacked, and we scarf the ends of the straight, slot-lying conductor-portions 6, or cut them at an angle, and do the same for the ends of the end-connectors l, and braze the two ends together as indicated at 22 in Fig. 3. By this means, a space 23 (Fig. 3) is left, which provides a clearance at the end of the stacking-bulges 25 of the coil-side 6, so as to facilitate the transition from the bulged stacked layers 6 and the plane stacked layers 1. Inasmuch as it has frequently been the practice to fabricate the straight coil-sides 6 and the formed end-connections 1' out of separate pieces, joined together, this method of construction does not add essentially to the cost. We believe it to be new, however, to utilize this form of construction in a winding in which the straight coil-sides have stacking bulges therein.

In operation, the high speed of rotation of the rotor-member 4 causes the internal gas-passages therein to operate as a centrifugal fan or pump for forcing the gas (or other cooling medium) to flow radially out of the rotor-member. The cooling medium enters through the openings ID in the end-plate 9, near the shaft, and the cooling-medium leaves through all of the radial openings in the periphery of the rotor-member, includingboth the radial openings 1 l in the retaining-ring 8, and the radial openings I"! in the slot-closing wedges IS. The air or hydrogen or other cooling medium thus enters the rotor at the end-openings Ill l0, and some of it flows axially inwardly into the rotor member, through the axially-disposed ventilating-spaces 12 of the several rotor-slots 5, and thence through the radial wedge-openings ll,

We claim as our invention:

1. A dynamo-electric machine having a slotted core, axially extending winding-portions lying in slots of said core, and means for cooling said winding-portions, characterized by said windingportions lying in a stack of superposed layers in said slots, each stack of slot-lying winding-portions having the bottom of the stack disposed near the bottom of its slot, and having the top of the stack extending up towards the slot-opening at the top of the slot, each of a plurality of said slots having an axially extending ventilating-space on at least one side of the stack of winding-portion layers in that slot, and slot-closing wedge-means for each slot, said slot-closing Wedge-means having one or more radial ventilating-openings therethrough in communication with the ventilating space or spaces of its slot and in approximate radial alignment therewith.

2. The invention as defined in claim 1, characterized by the winding-layers of each slot-lying stack comprising strap-conductors having internesting stacking-bulges for holding said stack in alignment.

3. The invention as defined in claim 1, characterized by the winding-layers of each slot-lying stack comprising strap-conductors having internesting stacking-bulges for holding said stack in alignment, and flat end-turn connectors connected to the ends of the several layers of said slot-lying axially extending winding-portions, said flat end-turn connectors being stacked in a plurality of stacks without stacking-bulges.

4. A dynamo-electric machine having a slotted core and a winding carried by said core, characterized by said winding comprising axially extending winding-portions lying in slots of said core, the winding-layers of each slot-lying stack comprising strap-conductors having internesting stacking-bulges for holding said stack in alignment, and fiat end-turn connectors connected to the ends of the several layers of said slot-lying axially extending winding-portions, said flat endturn connectors being stacked in a plurality of stacks without stacking-bulges.

HARRY E. CRINER. BENNIE A. ROSE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 507,194 Wood Oct. 24, 1893 1,985,040 Laffoon et al Dec. 18, 1934 FOREIGN PATENTS Number Country Date 283,698 Germany Apr. 22, 1915 

